Trac with FastCGI

​FastCGI interface allows Trac to remain resident much like with mod_python or mod_wsgi. It is faster than external CGI interfaces which must start a new process for each request. Additionally, it is supported by much wider variety of web servers.

Note that unlike mod_python, FastCGI supports ​Apache SuEXEC, i.e. run with different permissions than web server running with (mod_wsgi supports the WSGIDaemonProcess with user / group parameters to achieve the same effect).

Note for Windows: Trac's FastCGI does not run under Windows, as Windows does not implement Socket.fromfd, which is used by _fcgi.py. If you want to connect to IIS, you may want to try ​AJP/​ISAPI.

Simple Apache configuration

There are two FastCGI modules commonly available for Apache: mod_fastcgi and
mod_fcgid (preferred). The latter is more up-to-date.

The following sections focus on the FCGI specific setup, see also TracModWSGI for configuring the authentication in Apache.

Regardless of which cgi module is used, be sure the web server has executable permissions on the cgi-bin folder. While FastCGI will throw specific permissions errors, mod_fcgid will throw an ambiguous error if this has not been done. (Connection reset by peer: mod_fcgid: error reading data from FastCGI server)

Set up with mod_fastcgi

mod_fastcgi uses FastCgiIpcDir and FastCgiConfig directives that should be added to an appropriate Apache configuration file:

Set up with mod_fcgid

Configure ScriptAlias (see TracCgi for details), but call trac.fcgi
instead of trac.cgi. Note that slash at the end - it is important.

ScriptAlias /trac /path/to/www/trac/cgi-bin/trac.fcgi/

To set up Trac environment for mod_fcgid it is necessary to use
DefaultInitEnv directive. It cannot be used in Directory or
Location context, so if you need to support multiple projects, try
alternative environment setup below.

DefaultInitEnv TRAC_ENV /path/to/env/trac/

alternative environment setup

A better method to specify path to Trac environment is to embed the path
into trac.fcgi script itself. That doesn't require configuration of server
environment variables, works for both FastCgi? modules
(and for ​lighttpd and CGI as well):

Simple Cherokee Configuration

The configuration on Cherokee's side is quite simple. You will only need to know that you can spawn Trac as an SCGI process.
You can either start it manually, or better yet, automatically by letting Cherokee spawn the server whenever it is down.
First set up an information source in cherokee-admin with a local interpreter.

If the port was not reachable, the interpreter command would be launched. Note that, in the definition of the information source, you will have to manually launch the spawner if you use a Remote host as Information source instead of a Local interpreter.

After doing this, we will just have to create a new rule managed by the SCGI handler to access Trac. It can be created in a new virtual server, trac.example.net for instance, and will only need two rules. The default one will use the SCGI handler associated to the previously created information source.
The second rule will be there to serve the few static files needed to correctly display the Trac interface. Create it as Directory rule for /common and just set it to the Static files handler and with a Document root that points to the appropriate files: $TRAC_LOCAL/htdocs/ (where $TRAC_LOCAL is a directory defined by the user or the system administrator to place local trac resources).

Note:
If the tracd process fails to start up, and cherokee displays a 503 error page, you might be missing the ​python-flup package.
Python-flup is a dependency which provides trac with SCGI capability. You can install it on debian based systems with:

sudo apt-get install python-flup

Simple Lighttpd Configuration

The FastCGI front-end was developed primarily for use with alternative webservers, such as ​lighttpd.

lighttpd is a secure, fast, compliant and very flexible web-server that has been optimized for high-performance
environments. It has a very low memory footprint compared to other web servers and takes care of CPU load.

For using trac.fcgi(prior to 0.11) / fcgi_frontend.py (0.11) with lighttpd add the following to your lighttpd.conf:

Note that you will need to add a new entry to fastcgi.server for each separate Trac instance that you wish to run. Alternatively, you may use the TRAC_ENV_PARENT_DIR variable instead of TRAC_ENV as described above,
and you may set one of the two in trac.fcgi instead of in lighttpd.conf
using bin-environment (as in the section above on Apache configuration).

Note that lighttpd has a bug related to 'SCRIPT_NAME' and 'PATH_INFO' when the uri of fastcgi.server is '/' instead of '/trac' in this example (see ​#2418). This should be fixed since lighttpd 1.4.23, and you may need to add "fix-root-scriptname" => "enable" as parameter of fastcgi.server.

For using two projects with lighttpd add the following to your lighttpd.conf:

Note that field values are different. If you prefer setting the environment
variables in the .fcgi scripts, then copy/rename trac.fcgi, e.g., to
first.fcgi and second.fcgi, and reference them in the above settings.
Note that the above will result in different processes in any event, even
if both are running from the same trac.fcgi script.

Note It's very important the order on which server.modules are loaded, if mod_auth is not loaded BEFORE mod_fastcgi, then the server will fail to authenticate the user.

For authentication you should enable mod_auth in lighttpd.conf 'server.modules', select auth.backend and auth rules:

Note that lighttpd (I use version 1.4.3) stopped if password file doesn't exist.

Note that lighttpd doesn't support 'valid-user' in versions prior to 1.3.16.

Conditional configuration is also useful for mapping static resources, i.e. serving out images and CSS directly instead of through FastCGI:

# Aliasing functionality is needed
server.modules += ("mod_alias")
# Set up an alias for the static resources
alias.url = ("/trac/chrome/common" => "/usr/share/trac/htdocs")
# Use negative lookahead, matching all requests that ask for any resource under /trac, EXCEPT in
# /trac/chrome/common, and use FastCGI for those
$HTTP["url"] =~ "^/trac(?!/chrome/common)" {
# Even if you have other fastcgi.server declarations for applications other than Trac, do NOT use += here
fastcgi.server = ("/trac" =>
("trac" =>
("socket" => "/tmp/trac-fastcgi.sock",
"bin-path" => fcgi_binary,
"check-local" => "disable",
"bin-environment" =>
("TRAC_ENV" => "/path/to/projenv")
)
)
)
}

The technique can be easily adapted for use with multiple projects by creating aliases for each of them, and wrapping the fastcgi.server declarations inside conditional configuration blocks.
Also there is another way to handle multiple projects and it's to use TRAC_ENV_PARENT_DIR instead of TRAC_ENV and use global auth, let's see an example:

Relaunch lighttpd, and browse to http://yourhost.example.org/trac to access Trac.

Note about running lighttpd with reduced permissions:

If nothing else helps and trac.fcgi doesn't start with lighttpd settings server.username = "www-data", server.groupname = "www-data", then in the bin-environment section set PYTHON_EGG_CACHE to the home directory of www-data or some other directory accessible to this account for writing.

Simple LiteSpeed Configuration

The FastCGI front-end was developed primarily for use with alternative webservers, such as ​LiteSpeed.

LiteSpeed web server is an event-driven asynchronous Apache replacement designed from the ground-up to be secure, scalable, and operate with minimal resources. LiteSpeed can operate directly from an Apache config file and is targeted for business-critical environments.

Please make sure you have first have a working install of a Trac project. Test install with “tracd” first.

Create a Virtual Host for this setup. From now on we will refer to this vhost as TracVhost. For this tutorial we will be assuming that your trac project will be accessible via: